In a closed pump circuit such as may be used in a hydraulic system or for coolant in a refrigeration system, an expansion/reservoir vessel is used to store the pump fluid. The expansion/reservoir vessel must be able to accommodate coolant volume spikes. Previously, volume spikes caused by coolant expansion were accommodated in various ways, as by use of diaphragms in the wall of the vessel, etc.
In a computer liquid-cooling system, for example, the coolant may have significant volume changes through temperature variances as the system operates. If a closed pump circuit is desired to be employed, such volume spikes must be accommodated. For example, volume spikes are sometimes accommodated by pressure release diaphragms or valves.